Tribology is the study of friction lubrication and wear between surfaces in relative motion. As such it is relevant to many aspects of the modern world, from classic machine elements such as gears and bearings to medical devices such as hip implants. Reduction of tribological losses is key tool for the current drive to net zero emissions. 

This module will expand upon machine element theory and present important new topics such as fluid film lubrication, surface roughness, lubricant properties, friction and wear and frictional heating. 

You will develop the capability to numerically analyse and critically evaluate the operation and performance of  a range of tribological components and systems. 

LO1. Understand the importance of surface roughness in tribological contacts and its relevance to lubrication regimes [AHEP M1, M2].

LO2. Understand how the geometry and kinematics of contacts combined with lubricant properties can generate load carrying fluid films, and examine and characterise the performance of such films in common engineering applications (such as hydrostatic, hydrodynamic and elastohydrodynamic film bearings) [AHEP M1, M2] . 

LO3. Analyse and evaluate friction, wear and energy losses in a range of tribological systems [AHEP M1, M2, M12] . 

LO4. Apply the theory and techniques developed in this module to applications and problems beyond the examples explicitly covered during the course, including dealing with uncertain and ambiguous information [AHEP M2] . 

The Engineering Council sets the overall requirements for the AHEP (Accreditation for Higher Education Programmes). It is the standard used by the UK engineering profession to assess the competence and commitment of individual engineers and technicians and is in its 4th iteration. Link: ahep-fourth-edition. 

The module will be delivered in short blocks of teaching covering each subject on the syllabus.  These will combine face-to-face lectures, background material consisting of online videos and more extensive written notes, and tutorial sessions where example questions are considered.  

The lectures will deliver the core theory / techniques and the tutorials will provide opportunity to practise and discuss their application. Tutorials will be interactive with students encouraged to work through sample problems with guidance from academics. Extended ‘self-study’ notes will be provided alongside lectures, providing further information (for example step-by-step derivations) to aid the learning process and expand understanding.  

All face-to-face content will be published on Learning Central along with supplementary material (for example related research articles, computer programs / models and additional sample problems and solutions), however students are expected to attend all face-to-face lectures whenever possible. 

Alongside the lecture material, students will undertake a practical wear-testing experiment which will introduce lab skills and practical experience of wear testing and surface roughness measurement. The experiments will be undertaken in small groups, with individual reports being written based on the lab work.  

Subject specific skills: 

• You will learn new module specific skills such as the ability to analyse fluid-film lubrication problems, to evaluate friction and wear, and to characterise surface roughness. 

• You will increase your fluency in the following general areas of mechanical engineering: Ability to interpret designs and technical drawings, working with graphical design methods, solid mechanics (including aspects of statics, contact mechanics, kinematics and dynamics), fluid mechanics (including Couette and Pouseille flows) and mathematical analysis (including calculus and numerical methods).    

• You will develop experimental skills in friction and wear testing and surface roughness measurements.  

Professional and Practical Skills (AHEP4): 

• M1 Apply a comprehensive knowledge of mathematics, statistics, natural science and engineering principles to the solution of complex problems. Much of the knowledge will be at the forefront of the particular subject of study and informed by a critical awareness of new developments and the wider context of engineering 
• M2 Formulate and analyse complex problems to reach substantiated conclusions. This will involve evaluating available data using first principles of mathematics, statistics, natural science and engineering principles, and using engineering judgment to work with information that may be uncertain or incomplete, discussing the limitations of the techniques employed 
• M12 Use practical laboratory and workshop skills to investigate complex problems 

Transferrable/Employability Skills (Graduate Attributes): 

• Independent and Critical Thinkers 
  • ICT1: Identify, define, and analyse complex issues and ideas, exercising critical judgement in evaluating sources of information. 
  • ICT2: Demonstrate intellectual curiosity and engage in the pursuit of new knowledge and understanding 
• Reflective and Resilient 
  • RR3: Identify and articulate own skills, knowledge and understanding confidently and in a variety of contexts 

An individual exam is worth 60 % and covers  LO 1, 2, 4. The exam will take place in the Spring examination period. The exam will be 1.5 hours long and students will be required to attempt all 3 questions. The questions will present problems requiring a mixture of numerical analysis and problem related discussion. 

A coursework report is worth 40 % and covers LO 1 & 3.  You will be required to undertake a friction and wear test using standard wear testing equipment to evaluate the performance of a range of materials.  You will be required to perform the tests, take sample measurements before and after testing, analyse the results and make supporting calculations.  This will be written up in the form of a technical report.  

THE OPPORTUNITY FOR REASSESSMENT IN THIS MODULE: 

All components of this module will be available for re-assessment during the Resit Exam period.  You may be required to attend Cardiff to re-sit practical laboratory work if necessary.  

Opportunities for re-assessment is only permitted provided you have not failed more credit than in the resit rule adopted by your programme.  If the amount of credit you have failed is more than permitted by the relevant resit rule, you may be permitted to repeat study if you are within the threshold set for the Repeat rule adopted by your programme.  You will be notified of your eligibility to resit/repeat any modules after the Examining Board in the Summer period.  

All resit assessments will be held in the Resit Examination period, prior to the start of the following academic session. 

• Lubrication fundamentals:  lubricant properties, lubrication regimes, thermal and piezoviscous effects. 

• Analysis of fluid film lubrication:  Reynolds equation and its underlying assumptions. 

• Journal Bearings: long and short bearing theory with appropriate boundary conditions, numerical solutions and design charts. 

• Slider Bearings: Simple pad bearing, step bearings, tilting pads, thermal effects, numerical and design chart methods. 

• Lubrication of non-conformal contacts: rigid/isoviscous cases, piezeoviscosity and surface elastic deflection, elastohydrodynamic lubrication. 

• Hydrostatic Bearings: analysis of pressure distributions and fluid flows in hydrostatic bearings, consideration of capillary flows, basic layout of hydrostatic bearing systems. 

• Surface Roughness and Topography:  Methods of examining surfaces, microscopy, stylus profilometry. Surface profiles. Distribution of heights, spatial characteristics. Standards for description and quantification of surface roughness. Roughness parameters and their uses. 

• Friction and Wear:  Contact of rough surfaces, friction in elastic and plastic contacts, friction of polymers, wear models and mechanisms, wear testing. 

• Frictional Heating: point contact problems, including steady-state and transient models,  Peclet number, Division of heat, Blok formula for line contacts.